One of the first polymer case ammunition rounds for wide production in the Marine Corps will be for its heavy duty machine gun, the venerable M2 .50 caliber Browning Machine Gun.

The Marine Corps recently selected a company build polymer casings for .50 caliber ammunition, the largest direct fire, bullet projectile in the ground combat arsenal and a mainstay of machine gunning for nearly a century.

MAC LLC, a company out of Bay Saint Louis, Mississippi, won the sole source contract to deliver an estimated quantity of 2.4 million cartridges for the Corps over three years.

It will be producing both ball and armor-piercing rounds.

The weight savings sought by the Corps aims to cut 20 pounds off of the current weight of a can of .50 caliber ammunition, or a cut of up to one-third of the existing load.

Marine Corps Systems Command posted the request in April 2018 and awarded this contract this April 1, according to a posting on fbo.gov, a federal government business website.

A belt of 100 lightweight .50-caliber cartridges with 101 links will have to see a 15 to 30 percent weight reduction under the Corps’ requirements listing.

And no performance can be sacrificed — the new cartridge must meet the same ballistics requirements and lethality of the M33 projectile in service now.

Polymer is the new steel in many of weapons accessories and ammo casings.

The Corps authorized the use of polymer magazines for the M27 Infantry Automatic Rifle in recent years.

An ongoing Army program to build the Next Generation Squad Automatic Rifle, a parallel project to replace both the M4/M16 carbine/rifle and the Squad Automatic Weapon, is taking on submissions with polymer cased-telescoped ammunition.

One such version is the Textron Systems offering. Textron has spent years building a polymer-cased ammunition and essentially redesigned a weapon system around the new round.

All of these are part of larger efforts across the services to lighten the load with new materials, designs and configuration of everything from body armor to weapons systems and ammunition.

Originally posted by sigfreund:Another interesting tidbit.Will this really mark the introduction of reliable cartridges with plastic cases, or is it just one more pie in the sky announcement by the military?

great question

hard to believe we are transitioning from a supremely reliable design - the centerfire metallic cartridge - to a largely un-proven design

seems like advancements to the actual bullet itself would be where the 'improvements' would yield the best results -- effect on target

MAC LLC, a company out of Bay Saint Louis, Mississippi, won the sole source contract to deliver an estimated quantity of 2.4 million cartridges for the Corps over three years.

How does a company "win" a sole source contract? There apparently were no other competitive bidders. More like simply "awarded".

"Sole-source contract: is one in which the supply of product or service is only available from one company because it is the only one that can supply the needed product or service in a particular time when that product or service is needed. After exhaustive search and sourcing, only one company is ready to supply."

I would be interested in seeing the lot acceptance test criteria and watching said tests. IMO, heat build-up in the receiver is the biggest issue for polymer cased ammo (turning the chamber into a mass of plastic goo). Maybe the materials science in polymer is advancing significantly.

The Army's Armament Research, Development and Engineering Command in New Jersey and a number of companies have been researching and testing polymer-cased ammunition, along with case-telescoping ammunition, for the past 20 or so years.

Apparently Nammo has now taken a majority ownership position in MAC, LLC. Linky

IIRC, 50 cal goes straight from can to gun, no middle man with minimal handling of the belts compared to say, 7.62. Maybe the polymer cases will work here.

Unlike the Army, USMC has forces on mini-aircraft carriers (LPH or LHD) that are typically resupplied or deployed via helicopter. It doesn't seem the weight savings will be significant, but what do I know.

The Navy/Marine Corps 2019 and 2020 budget requests do not include these cartridges (ball and AP). Plus, the 2.4 million cartridges are over a 3-year period. My guess is that these are engineering development cartridges for the final R&D/operational testing before full acceptance/TC-STD. The last 2 years may be options to the contract (if all goes well).

Originally posted by Sig209:hard to believe we are transitioning from a supremely reliable design - the centerfire metallic cartridge - to a largely un-proven design

seems like advancements to the actual bullet itself would be where the 'improvements' would yield the best results -- effect on target

but what do I know

Well, a lot of people would argue the terminal ballistics of the .50 don't need much improving. For a given caliber, there is only so much you can do. There is a sweet spot for bullet weight to optimize effective distance. If you concede that the projectile weight is almost perfect for a given caliber, then the only place to shave weight is in the case or the powder, and obviously there is more potential in the case than the powder.

I hear they’re talking about putting the cap, powder, and bullet all together in a copper metal package. How reliable will that be?Once again the gummint just can’t leave a proven system well enough alone.

“The fundamental cause of trouble in the world today is that the stupid are cocksure while the intelligent are full of doubt.” — Bertrand Russell

Originally posted by smschulz:As I recall several years ago there were some polymer cased rounds being made > that failed miserably.I guess they fixed the issue, huh?

I find it very surprising that the polymer can handle the pressures.

In a firearm, the pressure is mostly taken up by the chamber and bolt face. A brass case would not stand up to the pressure, either, if not supported by those steel confines. That is why headspace and chamber diameter are so important.

flashguy

Texan by choice, not accident of birth

When they ask me, "Paper or plastic?" I just say, "Doesn't matter to me. I am bi-sacksual."

Originally posted by smschulz:As I recall several years ago there were some polymer cased rounds being made > that failed miserably.I guess they fixed the issue, huh?

I find it very surprising that the polymer can handle the pressures.

In a firearm, the pressure is mostly taken up by the chamber and bolt face. A brass case would not stand up to the pressure, either, if not supported by those steel confines. That is why headspace and chamber diameter are so important.

flashguy

Every time someone goes down the polymer case route it always ends the same way with case head seperations. They never seem to solve the issue, and I don't think they ever really will.